Associations between HPA axis functioning and level of anxiety in children and adolescents with an anxiety disorder.

The hypothalamus-pituitary-adrenal (HPA) axis becomes active in response to stress. Hence, increased levels of anxiety in children and adolescents may be associated with changes in HPA-axis functioning. The aim of this study was to test if level of anxiety or specific anxiety disorders were associated with basal HPA axis activity in children and adolescents with an anxiety disorder. In 99 8- to 16-year-olds with an anxiety disorder, basal cortisol levels were assessed. It was tested if (1) cortisol levels correlated with the level of self-reported anxiety and (2) if cortisol levels were different for individuals with different anxiety disorders. In girls, low levels of anxiety were associated with a stronger rise in early morning cortisol concentrations. In both boys and girls, harm avoidance predicted low cortisol concentrations after awakening. Separation anxiety and physical anxiety symptoms predicted cortisol concentrations at noon. Differences between individuals with different anxiety disorders were not found. More research is needed regarding mechanisms that explain the associations that were found, and to investigate if treatment may influence HPA axis functioning in children and adolescents with an anxiety disorder. (c) 2007 Wiley-Liss, Inc.